Let export formats set their download file name

[Logvin]

Gadgets with several export variants all download under the same name.

I have a gadget with about 10 subpages. Its ExportHandler returns one PDF format per page, and client.js renders the right page from gadgetExportFormatId. That part works great. The problem is that every file is named after the gadget, so I end up with 10 files called Report.pdf and rename them by hand.

Proposal

The fix is small: an optional fileName on GadgetExportFormat, without the extension. The Export menu uses it in place of the gadget's title.

File	Change
workshop-shared/src/api.ts	fileName?: string on GadgetExportFormat
workshop-backend/src/gadget-export.ts	The schema keeps it (1 to 128 characters) instead of stripping it
workshop-frontend/src/GadgetExportMenu.tsx	format.fileName ?? gadgetTitle
workshop-backend/src/agent.ts	One sentence in the ExportHandler instructions so the agent knows it exists

Formats without fileName behave exactly as they do today, and makeExportFilename already sanitizes the name.

Example from a gadget's ExportHandler:

{
  id: "overview-pdf",
  label: "Overview",
  mode: "browser",
  contentType: "application/pdf",
  fileExtension: ".pdf",
  fileName: "Overview",
}

Status

I've been running it on my own instance and it works as intended. The branch has tests for both the schema and the menu: https://github.com/Logvin/cloudflare-os/tree/export-file-name

Happy to open a PR if you're open to it.

AI Disclosure: This change was developed with Claude Code (via CFOS!) as a pair programming tool. I directed the approach, reviewed all changes, and tested it on my own deployment. I'm the author, Claude is my editor.

[Logvin]

This was fixed with PR 865: #865

Thanks @maxwellpeterson for jumping on this!